The inventors of the present invention have filed a Japanese patent application, JP 2003-103336 A, for a continuous riveter shown in FIGS. 12 through 34. This continuous riveter is composed of a main body D, a driver section E, a rivet supplying section F, and a valve section G. FIGS. 12 and 13 show the riveter with a push button of a trigger valve released. FIGS. 14 through 19 show the riveter with the push button of the trigger valve pushed.
The driver section E has a small-diameter oil cylinder 1 which branches away from the main body D to extend sideways and a large-diameter air cylinder 3 which drives an oil piston 2 of the oil cylinder 1.
The oil piston 2 serves as a piston rod of a piston 7 installed in the air cylinder 3, and the oil piston 2 and the piston 7 are unitarily formed.
The oil cylinder 1 is communicated with a chuck cylinder 8 through a hole 18 leading to an oil chamber 16, which is a space created between a jaw case piston 20 and a nose piston 28 in the chuck cylinder 8.
Denoted by P2 is a second port for supplying compressed air to a piston anterior chamber 4 of the air cylinder 3 and to an air chamber 15 (FIG. 16) that is located between the nose piston 28 and a rod cover 17. The second port P2 is communicated with a port f (FIG. 13), which is one of the exit side ports of an operation valve 53.
Denoted by P1 is a first port for supplying compressed air to a posterior chamber 5 (FIG. 14) that is positioned behind the piston of the air cylinder 3. The first port P1 is communicated with a port e, which is the other of the exit side ports of the operation valve 53 described later.
Denoted by P3 is a third port for supplying, at an advanced position of the piston 7 (FIG. 14), compressed air of the posterior chamber 5 of the air cylinder 3 to a pilot air circuit Y of the operation valve 53.
A storage case 47 of the rivet supplying section F is fixed to the lower end of the air cylinder 3 with a pin 27.
The oil cylinder 1 and the chuck cylinder 8 of the main body Dare unitarily formed while positioned at approximately right angles with respect to each other. A shank storing case 9 for receiving a shank R1, which is cut off of a blind rivet R, is set in an upper part of the interior of the main body D. The rivet supplying section F is attached to a lower part of the exterior of the main body D.
A vacuum ejector 12 for vaccumizing the interior of the shank storing case 9 is attached to the upper end of the shank storing case 9.
The chuck cylinder 8 has the rod cover 17 attached to its lower end, and has the jaw case piston 20 in its interior. The jaw case piston 20 is a bowl-shaped piston which opens at its upper end. When set in place, the jaw case piston 20 serves as a partition between an air chamber 14 which is above the jaw case piston 20 and the oil chamber 16 which is below the jaw case piston 20.
Positioned below the jaw case piston 20 is a tubular jaw case 21, which is fixedly attached to the lower end of the bowl-shaped piston. The inner face of the front end of the jaw case 21 is a tapered face 22 whose diameter gradually decreases toward the front end. A pair of jaws 25 are slidably inserted into the tapered face 22.
The jaws 25 are biased downward by a spring 23, which is housed in the jaw case 21, through a jaw pusher 24 having a sharp tip.
A shank recovery pipe 13 is inserted in the jaw case 21 and is inserted into the shank storing case 9 with the top of the shank recovery pipe 13 piercing a bottom plate of the shank storing case 9.
The nose piston 28 is placed below the jaw case piston 20, and serves as a partition between the oil chamber 16 which is above the nose piston 28 and the air chamber 15 which is below the nose piston 28. A tubular body 29 formed on the lower end of the nose piston 28 is slidably inserted through the rod cover 17, which forms the lower end of the chuck cylinder 8, and extends to the outside of the cylinder 8. A nose piece 32 is fit in the lower end of the tubular body 29.
In the state shown in FIGS. 12, 16, 17, and 18, the front end of the jaw case 21 is in contact with a lower wall 30 (FIG. 21) of the tubular body 29 and the front ends of the jaws 25 are in contact with the nose piece 32 protruding from the lower wall 30 in a V shape.
The vacuum ejector 12 is constantly in operation while the continuous riveter is in use, and collects, by suction through the shank recovery pipe 13, the shank R1 of the rivet R which is cut off upon caulking in the shank storing case 9. At the same time, the vacuum ejector 12 holds by a suction force a rivet that is inserted in the jaw portion of the jaw case 21 from the nose piece 32 of the tubular body 29 of the nose piston 28. The vacuum ejector 12 is therefore communicated directly with a compressed air source 50 through a conduit 60.
The above-described structure allows the vacuum ejector 12 to run constantly while the continuous riveter is in use. In this way, the suction force constantly acts on the shank recovery pipe 13, and through the shank recovery pipe 13, on the nose piece 32 at the front end of the tubular body 29 and on the jaws 25. Not only that the shank R1 cut off of the rivet R upon caulking is thus collected in the shank storing case 9 through the shank recovery pipe 13, but also that the suction force acts also on the rivet R inserted into the nose piece 32 from the front end of the tubular body 29 so that the rivet R can be held while being prevented from falling off.
As shown in FIGS. 12, 14, 16 through 18, and 20, the rivet supplying section F is equipped with a tape air cylinder 37 (see FIG. 20), a guide plate 43, and the storage case 47 for a rivet holder belt T.
The tape air cylinder 37 houses a tape piston 39 biased in a return direction by a spring 38 as shown in FIG. 20. A feed claw 41 is fixedly attached to a shaft 40 of the tape piston 39.
The guide plate 43 has, in section, a shape of the mirror image of the letter C to adapt to the rivet holder belt T and guide the rivet holder belt T. An elongated hole 44 is formed in the vertical face of the guide plate 43. The feed claw 41 protrudes from the elongated hole 44 so as to be capable of reciprocal movement. As shown in FIG. 20, the vertical face of the guide plate 43 also has a spring plate 46 for guiding the rivet holder belt T by pressing a vertical portion of the rivet holder belt T.
The blind rivet holder belt T (or rivet holder belt T) is formed of synthetic resin or paper, and as shown in FIG. 26, has an elongated body that is shaped in section like the mirror image of the letter C. The vertical portion of the rivet holder belt T is denoted by T3 and has rectangular upper tabs T1 and lower tabs T2 along its upper and lower edges at regular intervals. One upper tab T1 and one lower tab T2 make one pair. One pair of upper and lower tabs is separated from the next pair by a gap T7. The vertical portion T3 has feed holes which are each denoted by T4 and which are bored at regular intervals. A through hole T5 is formed in each upper tab T1 and in each lower tab T2. To set the rivet R in the belt, the rivet R is inserted from below the lower tab T2 into the through hole T5 of the lower tab T2 and the through hole T5 of the upper tab T1 until a head portion R3 of the rivet R comes into contact with the top face of the lower tab T2.
Such rivet holder belt T is stored in the storage case 47 in a wound state, and fed through the guide plate 43 from the front end first. Feeding of the rivet holder belt T is achieved by reciprocating motion of the tape piston 39 of the tape air cylinder 37 with the feed claw 41 engaged with the feed hole T4 of the rivet holder belt T.
The valve section G is as shown in FIGS. 13, 15, and 19. The operation valve 53 is attached to the air cylinder 3 at a position indicated by a dot-dash line. Denoted by 2 is a position pilot switching valve. Designated by 49 is a trigger valve attached at a position indicated by an inner dot-dash line, where the oil cylinder 1 and the chuck cylinder 8 intersect with each other. The trigger valve 49 is for pushing or releasing a push button 51.
In the drawings, reference numeral 50 represents a compressed air source such as a compressor, and ports h and o are opened to the air. The exit side ports e and f of the operation valve 53 are communicated with the first and second ports P1 and P2, respectively. The third port P3 is communicated with the pilot air circuit Y.
An exit side port m of the trigger valve 49 is communicated with a pilot air circuit X of the operation valve 53 and with a fourth port P4, which is at the upper end of the chuck cylinder 8. A port n of the trigger valve 49 is communicated with an entrance side port g of the operation valve 53.
A fifth port P5 is provided in the rod cover 17. The air chamber 15 is communicated with a port k of the tape air cylinder 37 through the fifth port P5, so that compressed air in the air chamber 15 is supplied to the tape air cylinder 37 through the port P5 from a groove 31 in a lower part of the tubular body 29 (FIG. 19) when the nose piece 28 rises to its upper dead point (FIG. 18).
The above-described continuous riveter of the prior art operates as follows.
The rivet holder belt T is stored in the storage case 47 of the continuous riveter usually in a wound state. When caulking is not performed, the riveter is in the state shown in FIGS. 12 and 13 with the push button 51 (trigger) released and the rivet R held in the nose piece 32 by the suction force of the vacuum ejector 12, thus preventing the rivet R from falling off.
When a rivet main body R2 of the rivet R is inserted in a hole of sheet metal 48 and the push button 51 is pushed as shown in FIG. 14, the trigger valve 49 moves as shown in FIG. 15 to cause compressed air to flow from a port s to the port n, then from the port g of the operation valve 53 to its port e, and then from the first port P1 into the posterior chamber 5 of the air cylinder 3. The air flow advances the piston 7, thereby advancing the oil piston 2 and causing oil in an oil chamber 6 to flow into the oil chamber 16 of the chuck cylinder 8. This pushes the jaw case piston 20 up by a certain distance and the jaw case 21 is accordingly raised.
In this case, the pair of the jaws 25 which are biased downward and brought into contact with the nose piece 32 by the spring 23 through the jaw pusher 24 depart from the nose piece 32 and move downward while sliding along the tapered face 22 of the jaw case 21. Due to the tapered face 22, the jaws 25 approach each other. This makes it possible for the jaws 25 to hold the shank R1 of the rivet R while the jaws 25 make an ascent. The ascent of the shank R1 effects caulking using the rivet R and then the shank R1 is cut off as the head portion R3 of the rivet R is stopped at the front end of the nose piece 32.
In this case, the air chamber 15 and the anterior chamber 4 of the air cylinder 3 are opened to the air through the second port P2 and the ports f and h of the operation valve 53, and thus the nose piston 28 is pushed downward and the jaw case piston 20 alone makes an ascent.
When the piston 7 is advanced as described above, compressed air in the posterior chamber 5 is supplied to the pilot air circuit Y through the third port P3 to advance the operation valve 53 so that the state shown in FIGS. 18 and 19 is reached. Then, compressed air from the compressed air source 50 flows through the ports s, n, g, and f in this order and is supplied to the second port P2. The compressed air of the posterior chamber 5 of the air cylinder 3 flows through the ports e and h in the order stated and is released into the atmosphere whereas compressed air of the pilot air circuit X and compressed air of the air chamber 14 flow from the third port 3 to the port m and then to the port o to be released into the atmosphere.
The jaw case piston 20 and the nose piston 28 are thus raised to their respective upper dead points as shown in FIGS. 16 through 18.
In FIG. 16, the oil piston 2 (and accordingly the piston 7) has returned and the nose piston 28 has risen to a position near the bowl-shaped piston to let compressed air blow into the vacuum ejector 12. The interior of the shank storing case 9 is therefore held under a vacuum. The nose piston 28 rises relative to the jaw case piston 20 to bring the lower wall 30 of the tubular body 29 into contact with the lower end of the jaw case 21. At the same time, the upper end of the nose piece 32 pushes the front ends of the jaws 25 up to unlock the jaws 25.
In FIG. 17, the jaw case piston 20 and the nose piston 28 each have finished halfway through their ascent and the shank R1 has been sucked into the shank storing case 9 through the shank recovery pipe 13.
In FIG. 18, the jaw case piston 20 and the nose piston 28 each have reached their respective upper dead points. With the pistons 20 and 28 at their respective upper dead points, compressed air is supplied from the fifth port P5 to the port K of the tape air cylinder 37 to send the tape piston 39 forward. This advances the feed claw 41 from one elongated hole 44 to another. Engaged with the feed hole T4 of the rivet holder belt T, the feed claw 41 pulls the rivet holder belt T out of the storage case 47 and moves the rivet holder belt T by one pitch along the guide plate 43. The tip of the shank R1 is thus set on the axial center below the nose piece 32.
Next, the push button 51 is released to bring the valve section G into the state shown in FIG. 13. The trigger valve 49 is returned to its original position by the force of the spring 52, thereby supplying compressed air of the compressed air source 50 to the pilot air circuit X of the operation valve 53 through the port m. This causes the operation valve 53 to retreat. At this point, compressed air of the pilot air circuit Y flows through the ports P3 and P2 in this order and then from the port f to the port h to be released into the atmosphere.
At the above valve position, compressed air flows through the port s of the trigger valve 49 and then the port m to be supplied to the air chamber 14 from the fourth port P4 whereas the compressed air in the air chamber 15 flows through the ports P2, f, and h in the order stated to be released into the atmosphere. This action causes both the jaw case piston 20 and the nose piston 28 to descend to their respective lower dead points, thereby putting the shank R1 of the rivet R in the opened jaws 25 through the nose piece 32 to be held. At the same time, the front end of the nose piece 32 descends while bending the upper and lower tabs T1 and T2 of the rivet holder belt T downward. The descent of the nose piece 32 will be described later with reference to FIGS. 21 through 24.
While the nose piece 32 descends, the supply of compressed air to the tape air cylinder 37 is stopped, allowing the compressed air in the tape air cylinder 37 to escape. The tape piston 39 therefore retreats to its initial position by the action of the spring 38. On the other hand, the rivet holder belt T which is prevented from moving in the reverse direction by a reversal stopper claw 45 remains stopped while the feed claw 41 is disengaged from the feed hole T4 and moved one pitch forward to engage with the next feed hole T4.
At this point, the rivet holder belt T is elastically pressed against the guide plate 43 by the guiding (misalignment preventing) spring plate 46 and therefore is securely engaged with the feed claw 41 without misalignment.
Preparations for the next caulking of a rivet T are thus completed.
The subsequent operations are identical with those described in the above. By repeating the above operations, caulking using the rivet R can be made in succession.
FIGS. 21 through 24 show how the nose piece 32 descends. In FIG. 21, one rivet R is fed and the head portion R3 of the rivet main body R2 is positioned inside the lower tab T2.
In FIG. 22, the shank R1 is inserted in the nose piece 32 while the front end of the nose piece 32 is in the process of bending the upper tab T1.
In FIG. 23, the nose piece 32 descends further to bend the upper tab T1 thoroughly. The shank R1 pierces through the nose piece 32 to be loosely inserted in the jaws 25. The head portion R3 of the rivet main body R2 is in contact with the front end of the nose piece 32 and has bent the lower tab T2 a little. The proximal end of the lower tab T2 is supported by the guide plate 43. With the support of the guide plate 43 and the resistance met by the head portion R3 in bending the lower tab T2, the rivet R is completely inserted into the nose piece 32 until stopped at the head portion R3.
In FIG. 24, the nose piece 32 has reached its lower dead point with the rivet R completely inserted in the nose piece 32. The lower tab T2 has been bent thoroughly though omitted from the drawing. FIG. 25 is an enlarged sectional view showing the nose piece 32 of the conventional tubular body 29.
Alternatively, the rivet supplying section F may be as shown in FIGS. 28 through 34. FIG. 28 is a bottom view and FIG. 29 is a view as seen from the direction of the arrow A—A of FIG. 28. FIG. 30 is a side view and FIG. 31 is a perspective view showing a guide plate portion. Structural components that are identical with those in the above-described prior art are denoted by the same reference symbols.
As shown in FIGS. 28 through 34, the guide plate 43 extended from the storage case 47 of the rivet supplying section F has a linear feed portion 43a of a given length, and has, beyond the linear feed portion 43a, a bent portion 43b where the direction of the vertical portion T3 of the rivet holder belt T is bent at a given angle β. The bent portion 43b of the guide plate 43 has a pressing plate 61, which guides the rivet holder belt T by pressing down on the vertical portion T3 of the rivet holder belt T and which stretches over a guide surface from the linear feed portion 43a to the bent portion 43b. An end 61a of the pressing plate 61 to which the rivet holder belt T advances is tapered to gradually widen in order to facilitate the ingress of the rivet holder belt T. Owing to the pressing plate 61, the blind rivet holder belt T that has been fed linearly is securely guided from the linear feed portion 43a to the bent portion 43b to be bent at the bent portion 43b. 
The guide plate 43 is for guiding the rivet holder belt T, and as shown in FIGS. 29 and 31, has guide walls 62, 62 to ensure that the blind rivet holder belt T travels without falling off the guide plate 43. The elongated hole 44 which enables the feed claw 41 to make a linear reciprocating motion is opened in the linear feed portion 43a of the guide plate 43. The tip of the feed claw 41 protrudes from the elongated hole 44. As shown in FIG. 28 (and FIG. 20), the feed claw 41 is coupled to the piston 39 of the tape air cylinder 37, and the tape air cylinder 37 puts the feed claw 41 into a linear reciprocating motion. The feed claw 41 is engaged with the feed hole T4 of the rivet holder belt T as shown in FIG. 32 and the rivet holder belt T is sent forward by one rivet in conjunction with the linear advance of the feed claw 41.
FIGS. 31 through 34 show step by step how the guide plate 43 is used. First, from the state shown in FIG. 31, the feed claw 41 sends the rivet holder belt T forward by one rivet as shown in FIG. 32. The rivet holder belt T thus enters the area under the pressing plate 61 and is bent along the bent portion 43b of the guide plate 43. At this point, the vertical portion T3 of the rivet holder belt T enters the area under the pressing plate 61 and is guided without fail because the front end 61a of the pressing plate 61 is tapered to gradually widen. Immediately after the belt is bent, the shank R1 of the rivet R arrives at a position that coincides with the axial center of the tubular body 29 of the nose piston 28 as shown in FIG. 32.
Then, the continuous riveter is put into operation to perform “caulking”. Because the rivet holder belt T is being bent at that moment, a gap L is created as shown in FIG. 28 between a pair of the upper and lower tabs T1 and T2 situated in the bent portion 43b at a portion immediately past the position where the rivet holder belt T extending from the linear feed portion 43a is bent and a pair of the upper and lower tabs T1 and T2 situated in the linear feed portion 43a at a position immediately before the bend position. The gap L prevents the pair of the upper and lower tabs T1 and T2 situated immediately before the bend position from bumping into the descending tubular body 29 as shown in FIG. 33. This makes it possible to reduce the interval between one rivet R and another rivet R as much as possible as compared with the prior art as shown in FIG. 28. In addition, the upper and lower tabs T1 and T2 on the bent portion 43b do not interfere with descent of the tubular body 29 since the rivet R has already been put in use and is no longer held by the upper and lower tabs (see FIG. 34).
As a result, because the interval (pitch) between one rivet R and another rivet R in the rivet holder belt T can be set small, the number of rivets R loaded per a given length of the rivet holder belt T can be increased and more rivets can be stored in the storage case 47 than in the prior art.
However, the conventional continuous riveter has a problem. That is, between the air chambers 4, 14, and 15 and the oil chambers 6 and 16 defined by the oil piston 2, the jaw case piston 20, and the nose piston 28, compressed air of the air chambers 4, 14, and 15 infiltrates into oil in the oil chambers 6 and 16 after repeated use, causing air bubbles in the oil. As a result, residual pressure develops in the oil, which leads to a failure in carrying out predetermined operations with reliability.
This point will be described in detail referring to drawings. FIG. 35 is an enlarged view corresponding to a portion A of FIG. 1. The piston 7 of the air cylinder 3 and the oil piston 2 of the oil cylinder 1 are unitarily formed, and the oil piston 2 separates the oil chamber 6 in the oil cylinder 1 from the air chamber 4 of the air cylinder 3. The oil cylinder 1 is sealed by a gasket 72 in order to prevent compressed air of the air chamber 4 from entering the oil chamber 6, and is sealed by a gasket 71 in order to prevent oil of the oil chamber 6 from entering the air chamber 4.
In the return step of the oil piston 2 (the step where the state of FIG. 14 is returned to the state of FIG. 16), however, compressed air supplied from the port P2 to the air chamber 4 of the air cylinder 3 pushes the air piston 7 back and accordingly the oil piston 2 is pulled to retreat. At this point, the oil side in the oil cylinder 1 (oil chamber 6) is pulled by the oil piston 2 and is set under negative pressure. Despite the sealing effected by the gaskets 71 and 72 for preventing air infiltration, repeated operation causes compressed air to enter the space between the gaskets 71 and 72 gradually in small amounts. The infiltrated air accumulates and ultimately climbs over the gasket 71, which borders the oil chamber 6, to enter the oil chamber 6 and cause air bubbles in the oil.
FIG. 36 is an enlarged view corresponding to a portion B of FIG. 1. The upper portion is the air chamber 14 defined by the jaw case piston 20 and the lower portion is the oil chamber 16. Gaskets 73 and 74 are provided in the jaw case piston 20 in order to prevent compressed air of the air chamber 14 from entering the oil chamber 16. However, repetition of the reciprocating motion of the jaw case piston 20 inevitably leads to infiltration of a minute amount of air into the space between the gaskets 73 and 74. The infiltrated air is gradually increased in pressure up to the level of the compressed air to rise and ultimately enter the oil chamber 16 from the gasket 74 as the oil side is put under negative pressure in the return step of the jaw case piston 20. Thus air bubbles are formed in the oil.
FIG. 37 is an enlarged view corresponding to a portion C of FIG. 1. The upper portion is the oil chamber 16 defined by the nose piston 28 and the lower portion is the air chamber 15. Gaskets 76 and 77 are provided in the nose piston 28 in order to prevent compressed air of the air chamber 15 from entering the oil chamber 16. The nose piston 28 rises when compressed air is supplied to the air chamber 15, and is lowered when the oil chamber 16 receives hydraulic pressure. Therefore, repetition of the reciprocating motion of the nose piston 28 causes air to gradually infiltrate in small amounts from the gasket 77 into the space between the gaskets 76 and 77. The infiltrated air accumulates in the space between the gaskets 76 and 77, and the accumulated air gradually enters in small amounts the oil chamber 16 from the gasket 76 as the oil of the oil chamber 16 is pulled by the oil piston 2 and put under negative pressure in the return step of the nose piston 28. Thus air bubbles are formed in the oil of the oil chamber 16.
As shown in FIG. 9, an aircraft rivet has a washer R4 in addition to a shank R1, a rivet main body R2, and a head portion (flange body) R3. When the conventional continuous riveter is in use, the vacuum ejector 12 runs constantly in order to prevent the rivet R from dropping off of the nose piece 32 as well as to collect, in the shank storing case 9, the used shank R1 which has been cut (broken) off, upon completion of caulking. Accordingly, the washer R4 remains pressed against the front end of the nose piece 32 by suction as shown in FIG. 10 and hinders loading of the next rivet R. Thus, the riveter cannot be used until the washer R4 is removed, which makes it impossible to perform riveting in succession.
Although in some cases the guide plate 43 of the rivet supplying section F is bent as shown in FIGS. 31 through 34, caulking can not be performed in an accurate manner with a conventional rivet holder belt.
Therefore, a first object of the present invention is to provide a continuous riveter in which, between air chambers 4, 14, and 15 and the oil chambers 6 and 16 defined by an oil piston 2, a jaw case piston 20, and a nose piston 28, compressed air of the air chambers 4, 14, and 15 is prevented from entering the oil chambers 6 and 16, so that no air bubbles are formed in the oil to enable precise operations.
A second object of the present invention is to provide a continuous riveter in which, even when a vacuum ejector 12 is in operation and the suction force is acting on a nose piece 32, or an aircraft rivet R provided with a washer R4 is used, the washer R4 can be dislodged from the nose piece 32 without being pressed against the nose piece 32 by suction.
A third object of the present invention is to provide a continuous caulking method of rivets by using a rivet holder belt T with which accurate riveting can be performed with a continuous riveter that has a bent guide plate 43 in a rivet supplying section F.